The present invention relates to a scanning system adapted to scan a flat document, or a bound document, such as a book. More particularly, the invention is directed toward a scanning system which detects the right hand edge of a book or document and accomplishes the scan function in a right-to-left scan.
Conventionally, prior art scan systems register a document on the left hand of a document platen and enable a scanning system which scans the document from left-to-right; that is, from the beginning of scan at the registration position to an end of scan location which is set for the length consistent with the document to be copied. This scanning orientation is satisfactory for most applications, but is less than satisfactory for those systems which afford a book copying capability by modifying a platen so as to have an angled edge portion sloping generally downward, whereby the bound part of a book is held to the corner position of the platen so that the entire surface of one page may be placed in intimate contact with the surface of the platen. Examples of such a system are disclosed in U.S. Pat. Nos. 3,775,008 and 4,068,950. Prior art copiers utilizing the corner book edge feature require a leftward pre-scan motion which inhibits required movement of the scanning mirrors. The problem presented by the pre-scan requirement is best illustrated by reference to FIG. 1. FIG. 1 shows a prior art, full-rate, half-rate, scanning system which is conventional for most present day commercial copiers. A book 10, opened to the 180.degree. position, is placed on the surface of platen 12. A scanning system includes an illumination lamp 14 and a full rate scan mirror 16. Lamp 14, associated reflector 15, and mirror 16 are adapted to move, as a unit, from left to right beneath the platen at a full rate (scanning) speed. A corner mirror assembly 18 is adapted to move from left to right at 1/2 the scanning speed to maintain a constant system conjugate. The image is reflected along optical axis 19, projected through lens 20 and reflected through mirror 22 onto the surface of a photoreceptor drum 28. This type of system requires that the scanning mirror undergo a pre-scan excursion to the left prior to initiation of the scan exposure cycle, with initial acceleration (and vibration damping) taking place in the pre-scan zone shown as PS. Distance PS is typically about 11/2". The start of scan position is identified as point S.sub.0. If an attempt is made to modify this prior art system by adding a book edge (shown dotted), the pre-scan motion of assembly 18 would be constrained because the assembly would run into the book edge before the pre-scan motion is complete. A prior art method and apparatus relating to a tilted scan mirror and lens to enable scanning into a book binding area is disclosed in co-pending U.S. patent application Ser. No. 07/276,589, assigned to the same assignee as the present invention whose contents are hereby incorporated by reference. This disclosure does not describe a right-to-left scan wherein the book or document edge is detected by a sensor array.
The present invention is directed to an electrophotographic reproduction machine which incorporates a platen having an angled book edge and which utilizes a scanning system which scans from right-to-left (instead of the conventional left-to-right). By changing the scan direction the need for a pre-scan distance PS is eliminated and replaced by a much shorter distance ES (end of scan) in which the scan components are stopped and the reverse scan implemented. The invention can be practiced in a normal document scan mode or in a book scan mode. In either mode of operation the document registration edge (start of scan position) is sensed by a sensor mounted to the scan carriage. The invention may be used in either a light lens scanning system using off-axis imaging to enable scanning into the center of a book binding area, or, alternatively, the invention can be used in a RIS type scanning system wherein a tilted gradient index lens array is used to transmit images from along the document surface, including the book binding area onto a photosensor array such as a CCD array.
More particularly, the invention is directed to an optical scanning and imaging system for scan/illuminating a document placed on a document platen and for projecting an image along an optical path onto a photosensitive image medium to form a latent image of the document thereon, said optical scanning and imaging system comprising, in combination, an elongated illumination means adapted to incrementally scan/illuminate said document beginning at a start of scan position S.sub.0 coinciding with the right-hand edge of said document, and an imaging means for transmitting light reflected from said document along an optical path onto said image media.